From cac18a2f4b25c087811028d74ee4552e382e3f29 Mon Sep 17 00:00:00 2001 From: Ihar Hrachyshka Date: Tue, 16 May 2017 07:53:43 -0700 Subject: arp: honour gratuitous ARP _replies_ [ Upstream commit 23d268eb240954e6e78f7cfab04f2b1e79f84489 ] When arp_accept is 1, gratuitous ARPs are supposed to override matching entries irrespective of whether they arrive during locktime. This was implemented in commit 56022a8fdd87 ("ipv4: arp: update neighbour address when a gratuitous arp is received and arp_accept is set") There is a glitch in the patch though. RFC 2002, section 4.6, "ARP, Proxy ARP, and Gratuitous ARP", defines gratuitous ARPs so that they can be either of Request or Reply type. Those Reply gratuitous ARPs can be triggered with standard tooling, for example, arping -A option does just that. This patch fixes the glitch, making both Request and Reply flavours of gratuitous ARPs to behave identically. As per RFC, if gratuitous ARPs are of Reply type, their Target Hardware Address field should also be set to the link-layer address to which this cache entry should be updated. The field is present in ARP over Ethernet but not in IEEE 1394. In this patch, I don't consider any broadcasted ARP replies as gratuitous if the field is not present, to conform the standard. It's not clear whether there is such a thing for IEEE 1394 as a gratuitous ARP reply; until it's cleared up, we will ignore such broadcasts. Note that they will still update existing ARP cache entries, assuming they arrive out of locktime time interval. Signed-off-by: Ihar Hrachyshka Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/ipv4/arp.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'net/ipv4/arp.c') diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index cb5eb649ad5f..6bc16a01f1ee 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -658,6 +658,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) unsigned char *arp_ptr; struct rtable *rt; unsigned char *sha; + unsigned char *tha = NULL; __be32 sip, tip; u16 dev_type = dev->type; int addr_type; @@ -729,6 +730,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) break; #endif default: + tha = arp_ptr; arp_ptr += dev->addr_len; } memcpy(&tip, arp_ptr, 4); @@ -839,8 +841,18 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) It is possible, that this option should be enabled for some devices (strip is candidate) */ - is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && - addr_type == RTN_UNICAST; + is_garp = tip == sip && addr_type == RTN_UNICAST; + + /* Unsolicited ARP _replies_ also require target hwaddr to be + * the same as source. + */ + if (is_garp && arp->ar_op == htons(ARPOP_REPLY)) + is_garp = + /* IPv4 over IEEE 1394 doesn't provide target + * hardware address field in its ARP payload. + */ + tha && + !memcmp(tha, sha, dev->addr_len); if (!n && ((arp->ar_op == htons(ARPOP_REPLY) && -- cgit v1.2.3 From 451495e016614a116c7b8b26e940062acfcbde93 Mon Sep 17 00:00:00 2001 From: Miguel Fadon Perlines Date: Thu, 5 Apr 2018 10:25:38 +0200 Subject: arp: fix arp_filter on l3slave devices [ Upstream commit 58b35f27689b5eb514fc293c332966c226b1b6e4 ] arp_filter performs an ip_route_output search for arp source address and checks if output device is the same where the arp request was received, if it is not, the arp request is not answered. This route lookup is always done on main route table so l3slave devices never find the proper route and arp is not answered. Passing l3mdev_master_ifindex_rcu(dev) return value as oif fixes the lookup for l3slave devices while maintaining same behavior for non l3slave devices as this function returns 0 in that case. Fixes: 613d09b30f8b ("net: Use VRF device index for lookups on TX") Signed-off-by: Miguel Fadon Perlines Acked-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/arp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/arp.c') diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 6bc16a01f1ee..bfa79831873f 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -437,7 +437,7 @@ static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) /*unsigned long now; */ struct net *net = dev_net(dev); - rt = ip_route_output(net, sip, tip, 0, 0); + rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev)); if (IS_ERR(rt)) return 1; if (rt->dst.dev != dev) { -- cgit v1.2.3